1. Field of the Industrial Applicability
The present invention relates in general to a trouble-diagnosable multifunction tester for use with a variety of electronic control units for installation in automotive vehicles, and more particularly to a trouble-diagnosable multifunction testing apparatus which is specifically adapted to display trouble-diagnosis output signals (diagnosis signals) received from such electronic control units in a vehicle, and/or to transmit a series of electric test signals to these electronic control units.
2. Description of the Prior Art
Recently, with the electronification of vehicles having reached a remarkable level in the automobile industry, a variety of electronic control units (ECU's) have been employed to handle many operative functions of a vehicle. Typical examples of such ECU's, include ones for the electronic control of suspension systems, four-speed automatic transmission (4 A/T), automatic cruising systems, electronically controlled fuel injection, and so forth. From each of these ECU's extends a single signal line or electric lead on which an electric error code or electric diagnosis signal (trouble-diagnosis output signal) is led from the ECU to be processed for further evaluation. As shown in FIG. 1, when n units of such electronic control units ECU1 through ECUn are provided, the trouble-diagnosis signals output from these units ECU1 through ECUn are collectively fed to a collective lead connector 12 for the signal lines which is, for example, provided in a fuse box 11 (see FIG. 2). This collective connector 12 is to be connected operatively by a complementary or counterpart connector from a diagnosis tester (not shown) so as that light emitting diodes 21 provided on the diagnosis tester emit light when the trouble-diagnosis signals are output from the ECU's on the vehicle [see FIG. 3(A)].
As shown, for instance, in FIG. 3(A), when a diagnosis code signal 22 is output from the signal line d of one of the ECU's, as shown in FIG. 3(B), a light emitting diode 21 is now caused to emit light repeatedly at such time intervals as 1.5 sec., 0.5 sec., 1.5 sec., 0.5 sec., etc. Then, upon receipt of this specific series of interruptions in the emission of light from the light emitting diode 21, it is possible to identify from which ECU this specific diagnosis code is being emitting to allow further diagnostic processing. In this manner, as it is essential to have the light emitting diode 21 actuated in accordance with a diagnosis code, such diagnosis code is set to be a relatively low velocity signal with a relatively wide pulse width.
Due to the fact that the conventional diagnosis codes are, as noted above, of a series of data which is unidirectionally fed from some of the ECU's installed in the vehicle to the tester and are inevitably transmitted at a relatively low velocity, it is not possible in practice for the tester to process them at a high enough processing rate. In addition, it is not practicable to have the diagnosis tester display such data which have been processed in the ECU's so that it may obtain enough data to diagnose the vehicle's operating conditions.